Mefloquine is a chiral molecule with two asymmetric carbon centres, which means it has four different stereoisomers . The drug is currently manufactured and sold as a racemate of the ( R , S )- and ( S , R )-enantiomers by Hoffman-LaRoche , a Swiss pharmaceutical company. Essentially, it is two drugs in one. Plasma concentrations of the (–)-enantiomer are significantly higher than those for the (+)-enantiomer, and the pharmacokinetics between the two enantiomers are significantly different. The (+)-enantiomer has a shorter half-life than the (–)-enantiomer. 
Chronic symptoms of a rather nonspecific nature are quite common after mild TBI (Glasgow Coma Scale score of more than 12; loss of consciousness, less than 30 minutes; PTA, less than 24 hours). Approximately one-half, one-quarter, and one-eighth of patients still have significant symptoms at 3, 6, and 12 months, respectively. 4 Typical symptoms include headaches, fatigue, dizziness, depression, and difficulties with concentration and memory, which are often complicated by anxiety symptoms related to travel and posttraumatic stress disorder. Alteration of cerebral blood flow during working memory tasks 1 month after injury and long-standing changes in fractional anisotropy—an MRI measure of white matter integrity—have been shown. 5
Distress or confusion tends to be episodic in nature. Once an episode has passed or if the psychiatric drug is not helping we may wish to stop taking the drug. If we want to reduce or stop our dependence on psychiatric medication, it is important to develop other ways of balancing mood and dealing with difficult mind states. It is also important to develop a support network around you that will support you in this coming off process. We recommend where possible people work collaboratively with their prescriber to negotiate the coming off process. Reducing medication can be a difficult process so it is important to prepare well before starting a reduction process.